1. Field of the Invention
The present invention relates to an intake air control apparatus provided with a fuel injection valve injecting fuel toward an internal combustion engine as well as controlling an amount of air toward the engine, and particularly relates to an intake air control apparatus for a motor cycle provided with a main throttle valve opening and closing an intake passage working with an accelerator grip operated by a driver and attached to a main throttle shaft, and a sub throttle valve opening and closing an intake passage at an upstream side from the main throttle valve on the basis of an operation of a motor driven in correspondence to an operating state of the engine and attached to a sub throttle shaft, in the intake passage provided through an inner portion of a throttle body.
2. Description of the Conventional Art
In the intake air control apparatus of the internal combustion engine mentioned above, at a starting time when an engine atmosphere temperature is cold (called as a cold starting time), an increase of an amount of air toward the engine is executed by making an opening degree of the main throttle valve open toward a first idle opening degree from an idling opening degree, and the sub throttle valve is made open to an approximately full-open state by a motor at a time of making the main throttle valve open to the first idle opening degree from the idling opening degree, whereby the opening degree of the main throttle valve is mechanically made open to the first idle opening degree from the idle opening degree on the basis of the opening motion of the sub throttle valve.
The conventional art mentioned above is shown in Japanese Unexamined Patent Publication No. 2005-90471.
A description will be given of the conventional art with reference to FIGS. 3 and 4.
FIG. 3 is a front view and FIG. 4 is a right side view of FIG. 3.
Reference numeral 10 denotes a throttle body in which an intake passage 11 is provided through an inner portion. In the intake passage 11, there is arranged a main throttle valve 13 attached to a main throttle shaft 12 rotatably borne to the throttle body 10. One end of the main throttle shaft 12 is arranged so as to protrude in a side direction (a left side in FIG. 4) from the throttle body 10, and a throttle drum 14 is arranged at the protruding end portion of the main throttle shaft 12 so as to be screwed. Further, a valve opening wire Wa and a valve closing wire Wb are locked to an accelerator grip G at one ends thereof, and the other ends of the valve opening wire Wa and the valve closing wire Wb are locked to the throttle drum 14. The vale opening wire Wa rotates the throttle drum 14 in a counterclockwise direction in FIG. 3 on the basis of a rotation of the accelerator grip in one direction executed by the driver, whereby the main throttle valve 13 opens the intake passage 11. On the other hand, the vale closing wire Wb rotates the throttle drum 14 in a clockwise direction in FIG. 3 on the basis of a rotation of the accelerator grip in the other direction executed by the driver, whereby the main throttle valve 13 closes the intake passage 11.
In the structure mentioned above, the valve opening wire Wa and the valve closing wire Wb are held via regulating tube members Bc and Bd inserted into support holes Ba and Bb formed at an upper end of a wire bracket B by bending, and a flat portion Be of the wire bracket B is screwed fixedly onto an outer end surface 10a (a left end surface in FIG. 4) close to the throttle drum 14 of the throttle body 10 by means of a screw C. In this case, the regulating tube members are omitted in FIG. 4.
Further, an opening degree state of the main throttle valve 13 in FIG. 3 indicates an idling opening degree state, and an idling opening degree is regulated by arranging an idle regulating screw D so as to be brought into contact with an idle control arm portion 14a formed on the throttle drum 14, and moving forward and backward the idle regulating screw D by screwing.
Reference numeral 15 denotes a sub throttle valve arranged in an intake passage 11a at an upstream side from the main throttle valve 13. The sub throttle valve 15 is attached to a sub throttle shaft 16 rotatably borne to the throttle body 10.
One end of the sub throttle shaft 16 is arranged so as to protrude to a left side in FIG. 4 from the throttle body 10, and a cam lever 17 provided with a cam surface 17a is arranged at the left protruding end portion of the sub throttle shaft 16 by screwing. In this case, a motor M rotationally driven in correspondence to an engine operating state is connected to the other end (a right end portion in FIG. 4) of the sub throttle shaft 16, whereby the sub throttle shaft 16 is electrically driven by the motor.
Reference symbol L denotes an intermediate link lever for transmitting a rotation of the cam lever 17 to the throttle drum 14. (In other words, the rotation of the sub throttle valve 15 is transmitted to the main throttle valve 13.)
The intermediate link lever L is arranged so as to be rotatably borne to an intermediate link lever support pin P provided toward an outer side (a left side in FIG. 4) so as to rise on an outer end surface Bg (a left end surface in FIG. 4 in a side facing to the throttle drum 14) of the flat portion Be of the wire bracket B via a collar E. Further, on the intermediate link lever L, there is arranged a roller T facing to the cam surface 17a of the cam lever 17, and there is attached a first idle regulating screw F facing to a first idle control arm portion 14b of the throttle drum 14.
In this case, at a time of the idle opening degree of the main throttle valve 13 in FIG. 3, a leading end of the first idle regulating screw F is not brought into contact with the first idle control arm portion 14b of the throttle drum 14.
In accordance with the intake air control apparatus mentioned above, at starting times under the engine atmosphere temperature being a room temperature and a high temperature, since the sub throttle valve 15 is not made open to the full-open state by the motor M, and the cam surface 17a of the cam lever 17 is not brought into contact with the roller T of the intermediate link lever L, the intermediate link lever L does not rotate, and the first idle regulating screw F is not brought into contact with the first idle control arm portion 14b of the throttle drum 14. Accordingly, the main throttle valve 13 is held to a predetermined idling opening degree, and the engine start is executed at the room temperature time and the high temperature time.
On the other hand, at a starting time under the engine atmosphere temperature being cold, the sub throttle shaft 16 is electrically rotationally operated by the motor M, and the sub throttle valve 15 is made open to an approximately full-open state. In accordance with the rotation of the sub throttle shaft mentioned above, the cam lever 17 is synchronously rotated largely in an opening direction (a counterclockwise direction in FIG. 3) of the sub throttle valve 15, whereby the cam surface 17a of the cam lever 17 is brought into contact with the roller T so as to synchronously rotate the intermediate link lever L in the clockwise direction.
Further, in accordance with the rotation in the clockwise direction of the intermediate link lever L, the first idle regulating screw F is brought into contact with the idle control arm portion 14a of the throttle drum 14 so as to rotate the throttle drum 14 in the counterclockwise direction, whereby the main throttle valve 13 is automatically made open toward the first idle opening degree regardless of the operation of the accelerator grip.
Accordingly, since the main throttle valve 13 is automatically made open to the first idle opening degree via the sub throttle shaft 16, the cam lever 17, the intermediate link lever L and the like on the basis of the rotational drive of the motor M at the cold starting time of the engine, it is possible to increase an amount of air heading for the engine, whereby it is possible to execute an improved cold start of the engine.